Abstract: A process for rapidly dewatering and drying calcium sulfate hemihydrate in a centrifuging and flash drying operation by ejecting the wet solids from the centrifuge bowl directly into the flash dryer's high velocity, high volume, heated air stream.

Abstract: A fiber-reinforced cementitious sheet is formed by first co-mixing in an air current reinforcing fibers such as glass fibers, and cementitious mineral materials in finely particulate form such as calcium sulfate hemihydrate, both in substantially dry form, depositing the mixture on a moving foraminous surface by means of the air current to form a sheet, applying water as by spraying in at least an amount which is stoichiometrically sufficiently to hydrate the calcium sulfate hemihydrate to the dihydrate form and to provide the necessary degree of plasticity to the mixture, densifying the sheet by compression, and setting and drying the sheet. A pair of sheets may be utilized as face sheets and, prior to setting, combined with a core formed of for example a calcium sulfate hemihydrate slurry, and the sheets and core then set and dried to form a paper-free gypsum board having excellent strength, surface hardness, and fire-resistant properties.

Abstract: A fiber-reinforced cementitious sheet is formed by first co-mixing in an air current reinforcing fibers such as glass fibers, and cementitious mineral materials in finely particulate form such as calcium sulfate hemihydrate, both in substantially dry form, depositing the mixture on a moving foraminous surface by means of the air current to form a sheet, applying water as by spraying in at least an amount which is stoichiometrically sufficient to hydrate the calcium sulfate hemihydrate to the dihydrate form and to provide the necessary degree of plasticity to the mixture, densifying the sheet by compression, and setting and drying the sheet. A pair of sheets may be utilized as face sheets and, prior to setting, combined with a core formed of for example a calcium sulfate hemihydrate slurry, and the sheets and core then set and dried to form a paper-free gypsum board having excellent strength, surface hardness, and fire-resistant properties.

Abstract: An improved process for forming cast articles of plaster reinforced with fibers is disclosed wherein low consistency plaster slurries that include a fluidizing agent and fibrous reinforcing materials are co-sprayed onto a sectionalized casting bed having a flexible membrane section connecting rigid sheet forming bed portions; allowed to stand in a horizontal position through initial stiffening; and then before the slurry has set, the sectionalized casting bed is reformed so as to produce a contoured shape to the gypsum cement sheet.

Abstract: Fire-resisting doors having a novel framing, that is the stiles and rails of the door, are disclosed. The door comprises preferably a thermal insulating core and conventional outer facing cover sheets and is framed with a particular combination of glass fibers and gypsum in a particular arrangement.